As a nitride semiconductor element based on nitride semiconductor, for instance, a light emitting diode (LED) is used in display devices, illumination and the like. Nitride semiconductor elements also include electronic devices such as high speed electronic devices and power devices.
Such a nitride semiconductor element is formed primarily on a heterogeneous substrate of sapphire, silicon (Si) or the like. However, defects and substrate warpage (cracks) are likely to occur due to the difference in lattice constant and the difference in thermal expansion coefficient. For higher device performance, it is important to reduce defects in the nitride semiconductor. There is demand for a technique for fabricating a nitride semiconductor crystal with few dislocations.